1. Field of Invention
The present invention relates to tree stump grinding teeth and to tree stump grinding wheel assemblies that include the same.
2. Description of Related Art
Conventional tree stump grinding machines include a tree stump grinding wheel assembly that comprises a vertically oriented wheel having a plurality of grinding teeth (which are sometimes also referred to in the art as “cutting teeth”) mounted on both side surfaces thereof. The wheel is typically mounted on an extension arm or boom of a grinding machine, which rotates the wheel at relatively high speed in a forward direction relative to the grinding machine. An operator of the grinding machine moves the rotating wheel in plunging and sweeping motions relative to a tree stump to be removed, which causes the grinding teeth mounted thereon to make contact with the tree stump. The grinding teeth grind mounted to the rotating wheel impact against the tree stump and thereby cut or otherwise pummel the tree stump into chips, chunks or pieces until it is removed, typically below the grade of the surrounding soil.
During tree stump removal operations, the grinding teeth are subjected to very large impact and abrading forces. Over time, these forces can cause one or more of the grinding teeth to break off and/or to wear out. When this occurs, one or more of the grinding must be replaced. Replacement of grinding teeth is often a time consuming process because the radial projection of each grinding tooth must be positioned in a predetermined optimal orientation before it is fastened to the wheel.
In some prior art tree stump grinding wheel assemblies, the grinding teeth are positioned directly into contact with a side surface of the wheel and are fastened directly thereto using fasteners such as bolts. An example of such a prior art assembly is shown in Bowling, U.S. Pat. No. 5,497,815. This patent discloses a one-piece grinding tooth that includes a mounting base having at least one substantially flat surface that directly contacts the wheel. The grinding tooth is fastened to the wheel using at least one bolt, which passes through a bore in the mounting base. In the embodiments illustrated in the figures, two bolts are used to fasten each grinding tooth to the wheel. In this arrangement, the bolts are solely responsible for holding the grinding tooth to the wheel. Thus, if the impact force applied to the grinding tooth were greater than the shear strength of the bolts, the bolts would fail and the grinding tooth would shear away from the wheel. The loss of mass caused by the shearing away of one or more grinding teeth from the wheel could cause the wheel to become unbalanced, which could create potentially damaging vibration in the grinding machine.
Another drawback with the use of a grinding wheel assembly and grinding teeth such as disclosed in Bowling is that the holes bored in the wheel to receive the bolts are exposed to the risk of damage due to impact forces imparted to the teeth, which can be communicated through the bolts to the holes bored into the wheel. This can cause the holes bored into the wheel to become deformed and otherwise compromised. Consequently, the fit and/or orientation of replacement grinding teeth will not be optimal, and replacement grinding teeth may wear prematurely and/or become more readily dislodged from the wheel.
Yet another drawback with the use of the grinding wheel assembly and grinding teeth such as disclosed in Bowling is that the side surfaces of the wheel are exposed to the risk of damage due to impact forces translated through the grinding teeth. The impact force imparted to the tooth can cause the at least one substantially flat surface of the mounting base in direct contact with the wheel to dent, gouge or otherwise create surface imperfections in the wheel. Once the surface of the wheel has been damaged, it can be very difficult to properly mount replacement grinding teeth to the wheel. In addition, moisture can wick between grinding tooth and the wheel, which can promote rust and/or corrosion of the wheel, grinding teeth and/or bolts.